Microstructure and fatigue properties of TiAl-based alloy with different tungsten contents

Microstructure and fatigue properties of TiAl-based alloys with different W contents were investigated. The results indicate that the grain size and lamellar spacing can be significantly refined, and the optimal W content on both the microstructure and fatigue property is about 1.00 at%. The amount of B2(ω) phase gradually increases with the increase in W content, and excessive B2(ω) phase located in the boundary of lamellar colony trends to be the weak region with low resistance against crack propagation. Another result is that with the increase in W content, the region of peritectic reaction is also enlarged. The interdendritic Al-rich region is another weak region against crack propagation. Both of these effects are responsible for the worse fatigue property of Ti–45.1Al–5Nb–1.40W–1.4B W alloy compared with that of Ti–45.7Al–5Nb–0.75W–1.4B alloy. Instability of fatigue property still exists, but it slightly reduces with the decrease in grain size and lamellar spacing.